Ever since the invention of the first stand alone hot water heater, owners of such water heaters have had to face the grim reality that the continuous use of the heaters over the years might result in a leak developing in the water heater tank. In the past, for most individuals, the appearance of a leak was evidenced by a gradually increasing presence of water or moisture in a region beneath and around the water heater. Accordingly most water leaks were detected early, by the occupants of the dwelling having the leaking water heater, usually before a catastrophically large leak developed. Single family homes typically locate the water heater in the basement on concrete floors with floor drains in close proximity to thereby minimize leaked water damage.
Today more than ever before, self contained condominiums are in the forefront of new home developments. It is not uncommon to find, especially in resort areas multistory condominium structures having hundreds of self contained units.
By self contained it is meant that each unit has its own furnace, air conditioning and hot water heater. The occupants of these condominiums are frequently transient in their use of the units, with many months or weeks arising where no one is present to observe the region surrounding a water heater to detect a leak. While most condominium owners set back the thermostat on the water heater to conserve energy while they are away it has been found that few consistently go one step further and turn-off the water heater. The circumstances just described create an environment in which an undetected hot water leak can result in extensive if not catastrophic damage to dwelling units on floors below the floor in which a water leak appears. Many days may elapse before the appearance of damage on lower floors will be discerned.
In view of the above it is not surprising that the problem of hot water leak detection has been addressed by an inventor.
Just such an example will be found in the patent to Frisby U.S. Pat. No. 4,252,088 which is directed to a differential switch for detecting leaks. The Frisby system depends upon the detection of a differential water flow rate across a water heater. Frisby operates on the principle that when there is no leak in the water heater then the flow rate into and out of the heater is the same. Frisby utilizes what must be categorized as extremely sensitive flow detection devices at both the inlet and outlet of the water heater. The flow detection devices detect the flow rate into and out of the heater and when the flow rate differs he shuts off the water supply. The assumption being that only when there is a leak will the flow rate be different. Frisby gives no indication as to whether his arrangement is sensitive enough to detect, say for example, a leak rate of twenty or thirty drops of leaked water per hour. While twenty to thirty drops per hour might seem negligible the cummulative effect over many weeks or months is surprisingly substantial and the resulting damage as great as if the leak was large and sudden. A further deficiency inherently present in Frisby resides in the absence of any means to ensure that upon leak detection that the volume of water in the heater is drained to a point where no damage will follow. It is also observed that no alarm is given as to the appearance of a leak.
In this regard it is noted that others in the field of boiler control have provided alarms when a condition within the boiler is inappropriate. One such system as shown in the patent to Williams U.S. Pat. No. 4,196,341 provides for the setting off of an alarm. The Williams system for monitoring the operation of an electric boiler also provides a control for a drain which drain control operates intermittently to aid in the continuous addition of fresh water to the boiler. Other examples of boiler condition detection and alarm generation will be found in the patents to Seklga, U.S. Pat. No. 4,256,258, titled, "Temperature Monitor and Alarm"; Kaczmarek et al, U.S. Pat. No. 3,834,357 titled, "Low Water Cut Off System".
In a somewhat unrelated field, rain detection and the sounding of alarm upon the start of precipitation is shown in the patent to Stroud, U.S. Pat. No. 1,109,481. The patent to Stroud is directed to a rain ennunciator which includes electrical contact members 16 and 17 having a hygroscopic element 20 position there between. When rain falls on the hygroscopic element 20 an electrical circuit is completed through the moisture between the two contacts 16, 17 which completes a circuit including a source of power and an alarm bell 13,14.
In Stroud the drying out of the hydroscopic material results in the interruption of the circuit and the bell ceases to ring.
It is against this background of teachings of the prior art that the invention to be described provides a water leak control circuit for use with a water heater having an inlet and a drain. The water leak control circuit simultaneously detects leaks, actuates an alarm, shuts off a water supply to the water heater, drains the heater and releaseably maintains the alarm activated, the water supply shut off and the heater drained. The just enumerated features are collectively and singularly absent from the prior art reviewed herein before.